This invention relates to an ablative material for use in the fabrication of nose tips for re-entry vehicles and to a method for its manufacture. More particularly, this invention relates to a fine textured, three-dimensional, reinforced carbon-carbon composite nose tip material having an improved shape stability in ablation/erosion environments and improved mechanical properties in comparison with presently known nose tip materials.
Recent advances in the field of aerospace technology have created a need for high strength, temperature resistant materials that possess the necessary properties needed to protect re-entry vehicles from the severe temperatures encountered within their re-entry environment. Re-entry vehicles are especially vulnerable to the stress and strain induced by their re-entry environment and require shapestable nose tips capable of surviving those stresses. Existing carbon-carbon materials have proven somewhat effective as materials for nose tip application and show adequate thermal stress performance. Unfortunately, however, these materials are deficient in mechanical strength and show unpredicted anomalies in their ablation characteristics.
With the present invention, however, it has been found that re-entry vehicle nose tips having superior re-entry performance characteristics in combination with high mechanical strength can be fabricated from a three dimensional fine textured carbon-carbon composite produced in accordance with this invention. The fiber ratio of the 3-D composite material in different directions was adjusted to provide higher transverse and shear reinforcement than in standard 3-D materials known heretofore. The adjustment of the axial or "Z" direction versus the lateral or "X" or "Y" direction provides an unexpected flexibility that makes the material especially useful in shell as well as plug nose constructions.